Laser comprising a laser medium

Abstract

A laser having a standing wave resonator including a first resonator section, which has at least a first end mirror and a second resonator section, which has at least a second end mirror. At least one of the optical elements of the first resonator section is embodied in focusing fashion. Accordingly, the beam axes of the laser beam which arrives upon respective tiltings of at least one of the optical elements in the second resonator section have at least one crossing point, which lies in the pump region of the laser medium or is at a distance from the pump region which amounts to less than the Rayleigh length. The radius (w) of the laser beam is less than five times the radius (w) of the laser beam in the pump region of the laser medium.

1 . A laser comprising a laser medium, which is excited in a pump region, and a standing wave resonator, which includes optical elements, by which a laser beam, which has a beam axis and penetrates the laser medium, is guided and which comprise a first end mirror and a second end mirror, wherein the resonator comprises a first resonator section, which has at least the first end mirror, and a second resonator section, which has at least the second end mirror, wherein at least one of the optical elements of the first resonator section is a focusing optical element, by which the beam axes of the laser beam, which result upon respective tilts of at least one of the optical elements arranged in the second resonator section, have at least one intersection point, and wherein said intersection point or one of said intersection points of the beam axes of the laser beam lies in the pump region of the laser medium or has a distance from the pump region which is less than a Rayleigh length, which corresponds to a section of the laser beam which lies between the laser medium and a closest one of the focusing optical elements of the first resonator section, a radius (w) of the laser beam, at least over a section of the laser beam which lies between the laser medium and the closest focusing element of the first resonator section, is less than five times a radius (w) of the laser beam in the pump region of the laser medium. 
     
     
         2 . The laser as claimed in  claim 1 , wherein the radius (w) of the laser beam in the entire first resonator section, is less than five times the radius (w) of the laser beam in the pump region of the laser medium. 
     
     
         3 . The laser as claimed in  claim 1 , wherein only one of the optical elements of the first resonator section is the focusing optical element. 
     
     
         4 . The laser as claimed in  claim 1 , wherein a focal length of the focusing optical element of the first resonator section closest to the laser medium is less than 100 mm. 
     
     
         5 . The laser as claimed in  claim 4 , wherein the focal length of the focusing optical element of the first resonator section closest to the laser medium is less than 20 mm. 
     
     
         6 . The laser as claimed in  claim 1 , wherein the first end mirror is a concave mirror. 
     
     
         7 . The laser as claimed in  claim 1 , wherein the first end mirror is a planar mirror. 
     
     
         8 . The laser as claimed in  claim 1 , wherein the focusing optical element of the first resonator section closest to the laser medium is a concave mirror. 
     
     
         9 . The laser as claimed in  claim 1 , wherein the resonator is folded by one or more folding mirrors. 
     
     
         10 . The laser as claimed in claims,  claim 1 , wherein the laser is a pulsed laser. 
     
     
         11 . The laser as claimed in  claim 1 , wherein the radius (w) of the laser beam in the pump region of the laser medium is less than 250 μm. 
     
     
         12 . The laser as claimed in  claim 1 , wherein at least two of the optical elements of the resonator, which are arranged at different distances from the first end mirror with respect to an unfolded resonator, are integrally designed with one another or rigidly connected to one another and are jointly installed on a carrier part of the resonator. 
     
     
         13 . The laser as claimed in  claim 12 , wherein the at least two optical elements, which are integrally designed with one another or rigidly connected and are jointly installed on the carrier part, have optical surfaces, which are curved and have at least one of different centers of curvature or radii of curvature or which are flat and lie in planes at an angle to one another, or of the at least two optical elements which are integrally designed or rigidly connected and are jointly installed on the carrier part, at least one has a curved optical surface and at least one has a flat optical surface. 
     
     
         14 . The laser as claimed in  claim 12 , wherein the at least two optical elements which are integrally designed or rigidly connected and are jointly installed on the carrier part are two folding mirrors, wherein the laser beam is deflected by at least one further folding mirror between the deflections on the two folding mirrors. 
     
     
         15 . The laser as claimed in  claim 12 , wherein the at least two optical elements, which are integrally designed with one another or rigidly connected to one another and are jointly installed on the carrier part, upon a tilt in a same direction, have opposing effects on at least one of a displacement or an angle change of the beam axis of the laser beam in another of the optical elements of the resonator or in the laser medium. 
     
     
         16 . The laser as claimed in  claim 15 , wherein the at least two optical elements, which are integrally designed with one another or rigidly connected to one another and are jointly installed on the carrier part, upon a tilt in the same direction, have opposing effects on at least one of the displacement or the angle change of the beam axis of the laser beam in an optical element of the resonator acting as the decoupler for the output beam. 
     
     
         17 . The laser as claimed in  claim 1 , wherein the laser is a solid-state laser. 
     
     
         18 . The laser as claimed in  claim 1 , wherein a distance of the pump region of the laser medium from the closest focusing optical element of the first resonator section is less than three times the value of the Rayleigh length, which corresponds to the section of the laser beam which lies between the laser medium and the closest focusing optical element of the first resonator section. 
     
     
         19 . The laser as claimed in  claim 1 , wherein the resonator is designed as folded and has at least one folding mirror, which deflects the laser beam, for this purpose, and an unfolded length of the resonator is greater than 1 m. 
     
     
         20 . The laser as claimed in  claim 1 , wherein a length of the first resonator section is less than one-fifth of a length of the second resonator section, and an unfolded length is used in the case of a folded design of the resonator by at least one folding mirror. 
     
     
         21 . The laser as claimed in  claim 1 , wherein the first resonator section includes further optical elements, which interact with the laser beam between the first end mirror and the laser medium. 
     
     
         22 . The laser as claimed in  claim 1 , wherein the second resonator section includes additional optical elements, which interact with the laser beam between the laser medium and the second end mirror. 
     
     
         23 . The laser as claimed in  claim 10 , wherein the laser is a mode-coupled laser.